Optaros' "Social Ecommerce Ebook" makes for great reading if you are trying to optimize the performance of your ecommerce site. You can download it here.
They make the points that: 1. higher levels of shopper engagement on retail sites drive improved business performance, and 2. social commerce tools are a powerful way to drive engagement.
A couple highlights: From the Harvard Business Review Article, "In Ecommerce, More is More", they cite,
The majority of managers we spoke to in our global study told us they believe that a broad array of information diverts attention from the core offerings. But we found it helps customers search for solutions, invites them to think of all the ways the core products might add value to their lives, wins their loyalty, and entices them to buy. In fact, we found that exploiting consumers’ desire for engagement is the single dominant driver of superior shareholder value for e-commerce companies.
In the section titled "Making Shopping a Social Experience," (p.44 on) they cite an article in the Wall Street Journal on the benefits of social shopping. (The article features the positive results Teavana and Compsource are seeing from their TurnTo implementations!) Their "Business Takeaway":
People like to go shopping with others when shopping in person. With Facebook Connect and other social shopping applications, you can replicate this experience for your customers online.
The bottom line of their study (well, it's actually more like the title): "Retailers Achieve Higher Conversion Rates Using Social Shopping."